Detection of non-homogeneities in a continuous filter rod

ABSTRACT

A device for detecting isolated occlusions in a conveyed continuous rod in the tobacco industry includes a light source for irradiating the continuous rod with the aid of a light-transmission method. A sensor is disposed for at least partially detecting brightness caused by the light source being transmitted in the continuous rod. An evaluation unit detects the presence of isolated occlusions in the continuous rod on the basis of the detected brightness.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority of German Application No. 10 2005 012 811.4, filed on Mar. 17, 2005, the subject matter of which is incorporated herein by reference. Each U.S. and foreign patent and patent application mentioned below is also incorporated herein by reference.

BACKGROUND OF THE INVENTION

The invention relates to a device for detecting isolated occlusions in a conveyed continuous rod in the tobacco industry, in particular in a continuous filter rod, wherein a light source illuminates the continuous rod by a light-transmission method. A sensor at least partially detects areas of brightness in the continuous rod, caused by the light source.

The invention furthermore relates to a method for detecting isolated occlusions in a conveyed continuous rod in the tobacco industry, in particular a continuous filter rod. The continuous rod is irradiated by a light source and wherein the brightness in the continuous rod caused by the light source irradiation is at least partially detected with the aid of a sensor.

The invention furthermore relates to a continuous rod-producing machine in the tobacco industry, in particular a filter-rod maker.

A known method for testing a conveyed continuously advancing rod, in particular a continuous cigarette filter rod, is described in unexamined published patent application DE-A-27 32 520. The '520 application describes sections containing different types of material and/or differently embodied sections that follow successively and continuously. In this known method, a light beam extending nearly perpendicular to the plane for the longitudinal axis of the continuous filter rod is introduced at one location into the filter rod, and the brightness value measured at a distance thereto by means of a photo-electronic component, meaning at a location on the continuous filter-rod outside which is at least nearly in the same plane as the one for the light ray. The measuring result is then evaluated in an evaluation circuit that is electrically connected to the photo-electronic component.

A device for testing multi-component cigarette filters during the manufacturing process, following the continuous attachment of filter elements in a tube-shaped wrapper, is furthermore disclosed in U.S. Pat. No. 4,001,579 which corresponds to patent document DE-C-25 10 502.

SUMMARY OF THE INVENTION

Starting with the above-mentioned prior art, it is an object of the present invention to detect capsules or similar items purposely inserted into a continuous transverse axial conveyed filter rod.

The above and other objects are achieved according to an exemplary embodiment of the invention in which there is provided a device for detecting isolated occlusions in a conveyed continuous rod in the tobacco industry, in particular a continuous filter rod, comprising: a light source for irradiating the continuous rod by a light-transmission method, a sensor for at least partially detecting areas of brightness caused by irradiation from the light source, and an evaluation unit for detecting the presence of isolated occlusions in the continuous rod based on the detected areas of brightness.

During the production of continuous filter rods, non-homogeneities or occlusions, for example in the form of added bodies such as flakes or capsules but also in the form of holes, are inserted and/or generated either purposely or isolated in the otherwise homogeneously embodied continuous filter rods. The invention is designed to determine the existence of the non-homogeneities or occlusions, as well as the correct location therein in a continuous filter rod and/or in an individual filter, and to evaluate these by the device according to the invention. The distance between the occlusions as seen in the longitudinal axial direction and/or the conveying direction for the continuous rod can furthermore also be detected. For this, the conveyed continuous filter rod is irradiated and a photodiode is used to receive the light which passes through the continuous filter rod and/or the corresponding brightness profile. Following this, the brightness profile is used to determine whether the continuous filter rod contains a non-homogeneous area.

According to an embodiment of the invention, the speed for conveying the continuous filter rod can furthermore be used to detect the spacing in the longitudinal axial direction between the non-homogeneities. The detection according to the invention may also determine the dimensions of the occlusion and/or the non-homogeneous area with the aid of the continuously detected brightness profiles and the conveying speed for the continuous rod. This is achieved in another aspect of the invention by using an evaluation unit to which the signals and/or the detected brightness profiles from the sensor are transmitted.

It is furthermore advantageous if an imaging device is provided for imaging the brightness of the continuous rod on the sensor. As a result of this measure, the opening angle for the receiving optic is minimized and an imaging optic and/or device is used on the receiver side. For example, a smaller area of brightness in the continuous rod and/or the brightness profile, caused by the light source, is detected on a photo-sensitive layer of a photo-sensor.

The imaging device is advantageously provided with at least one lens and is thus embodied as an optical device.

It is furthermore advantageous if a measuring device is constituted by the light source, imaging device, and sensor. According to another exemplary embodiment at least two of such measuring devices are provided for the continuous rod. In particular, the at least two measuring devices are arranged transverse to the longitudinal axis of the continuous rod, preferably in a single plane.

A light propagation cone for the light emitted by the light source is minimized in the continuous filter rod if the light source is embodied as a laser light source, so that the continuous filter rod and/or the rod-shaped article to be examined, which is conveyed in longitudinal axial direction, is admitted with fan-shaped or point-shaped light. The detection quality is improved with a reduced light propagation cone in the continuous rod. The continuous filter rod is preferably irradiated by a laser which emits light in the red visible range, wherein laser light of this type typically has a wavelength in the range of 655 nm.

At least one diaphragm is furthermore provided in the beam path between the imaging device and the sensor.

According to another aspect of the invention, there is provided a continuous rod-producing machine in the tobacco industry, in particular a filter production machine and/or a filter rod maker, equipped with a device according to the invention for detecting isolated occlusions in a conveyed continuous rod in the tobacco industry. To avoid repetition, the preceding explanation concerning the device for detecting isolated occlusions is expressly referred to.

According to yet another exemplary embodiment of the invention, there is provided a method for detecting isolated occlusions in a conveyed continuous rod in the tobacco industry, in particular a continuous filter rod, wherein the rod is irradiated by a light source with the aid of the light-transmission method and wherein the brightness caused by the light source in the irradiated continuous rod is at least partially detected by a sensor. The detected brightness is used for determining the presence of isolated occlusions in the continuous rod.

The method according to the invention is based on the principle of detecting and identifying on a filter-rod maker and/or system the number and/or locations of inserted non-homogeneities and, if necessary, also the longitudinal axial spacing between the occlusions in a continuous filter rod by using light, and in particular laser light. The light conductivity is reduced owing to the non-homogeneities in the continuous filter rod, thus resulting in a brightness profile that differs from the profile of a filter rod section without non-homogeneity. The change in the brightness profile due to the occlusion is significant enough to allow detecting the non-homogeneity in the continuous filter rod. The difference in the light conductivity between the continuous filter rod material and the inserted non-homogeneity results in a signal that can be evaluated.

It is advantageously proposed that the brightness is imaged at least in part on the sensor with the aid of an imaging device.

The continuous rod is furthermore irradiated by means of a laser light source which preferably emits light in the visible red light range.

According to one embodiment, it is advantageous if the continuous rod is irradiated with the aid of at least two light sources.

According to another embodiment of the method, the position and/or the number of occlusions are identified with the aid of the detected areas of brightness.

It is furthermore advantageous to remove the continuous rod and/or the continuous filter rod or a section of the continuous rod and/or the continuous filter rod if the detected brightness values differ from predetermined control values.

An evaluation device can advantageously be used to detect the presence of occlusions in the continuous rod and/or the continuous filter rod.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the invention will be further understood from the following detailed description of the exemplary embodiments with reference to the accompanying drawings.

FIG. 1 is a schematic representation showing a filter-rod maker, provided with a detection device according to the invention.

FIG. 2 is a longitudinal section through an embodiment of a detection device according to the invention.

FIG. 3 is a cross section through a second embodiment of a detection device according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

In the drawings, the same and/or similar elements or parts are provided with the same reference numbers and will not be introduced again.

FIG. 1 shows a schematic view from the side of an apparatus for producing a continuous filter rod, in particular for producing cigarette filters and similar types of smoking articles. This apparatus includes two main structural components: a filter-tow processing machine 1 for producing an endless band of filter material and/or filter-tow material; and a processing machine 2 for producing wrapped individual filter rods.

The filter-tow processing machine 1, for example a machine of the Type AF2, AF3 or AF4 by the Assignee of the present application, which is known in the tobacco industry, is provided with a roller pair 3 for continuously pulling an endless band of filter material 4 from a bale 6. After being removed from the bale 6 and on its way to the roller pair 3, during which it is guided across a deflection roller 5, the filter-tow band 4 passes by two air nozzles 7 and 8. These air nozzles serve to spread out and loosen up the weave of the filter-tow band 4. The roller pair 3 is followed by two additional roller pairs 9 and 11, between which an application device 12 is arranged for applying plasticizer to the spread-out filter-tow band 4 that is guided between the roller pairs 9 and 11.

The roller pairs 3 and 9 jointly form a stretching device. The speed of the roller pair 3 is lower than the speed of the roller pair 9 and can be changed by means of a drive unit 14, for which the transmission ratio can be changed with an adjustment motor 16. The speed ratio between the roller pairs 3 and 9 predetermines the degree of stretching of the filter material band 4. For the exemplary embodiment shown herein, the rollers of the roller pair 3, which function as braking rollers, are driven. However, they can also be operated in the form of drag rollers which function as braking rollers due to the frictional conditions.

The roller pairs 3, 9 and 11 can be driven by means of a main drive motor 13 and via the belt drives 13 a to 13 c. One or several separate, individually controllable drives can also be provided for the roller pairs in place of a main drive motor 13.

The processed filter material band 4, which has been sprayed with plasticizer, forms a continuous filler material rod 44 which travels via the roller pair 11 from the filter-tow processing machine 1 to an intake funnel 17 of the processing machine 2, for example a machine of the Type KDF 2, KDF 3, or KDF 4 by the Assignee of the present application, which is known in the tobacco industry.

The continuous filler material rod 44 is compacted in the processing machine 2 and is placed onto a wrapping tape 21, pulled from a bobbin 18, and coated with glue by means of a glue applicator 19. The wrapping material tape 21 and the compacted filler material rod 44 are moved to a format belt 22 which moves both components through a format machine 23 where the wrapping tape 21 is wrapped around the continuous rod 44 of filter material, thereby creating an endless filter rod 24. This endless rod passes through a smoothing iron and/or a cooling section in which the glue on the overlapping seam hardens.

A smoothing iron is provided at this location if the glue applied to the wrapping tape is wet glue, wherein the seam is dried in the smoothing iron. A cooling section is provided if the wrapping tape 21 is provided with hot-melt glue, which is hardened by cooling it in the cooling section 26. Following this, the continuous filter rod 24 is transported through a detection device 100 according to the invention, so as to locate non-homogeneities purposely introduced into the continuous filter rod 24 with respect to their location and spacing.

Individual filter rods 28 are then cut continuously from the filter rod 24 by a knife apparatus 27 and are subsequently transferred by an accelerating device 29 to a delivery drum 31, in which they are conveyed while positioned transverse to the conveying direction. From the delivery drum 31, the filter rods are moved to a delivery belt 32 for conveying them to a different processing machine or to an intermediate storage location.

FIG. 2 shows a longitudinal section through an embodiment of a detection device 100 according to the invention, comprising a laser light source 122 and a sensor 114, arranged opposite the laser light source 122. A continuous filter rod 24, produced with purposely inserted occlusions or non-homogeneities 130, is conveyed between the laser light source 122 and the sensor 114.

The continuous filter rod 24 of cellulose acetate contains regularly spaced apart occlusions or non-homogeneities 130 on the inside. The occlusions or non-homogeneities 130 are disposed preferably near the center axis of the continuous filter rod 24. The occlusions or non-homogeneities 130 are purposely inserted into continuous filter rod 24, for example with the aid of a machine as disclosed in European patent document EP-A-1 012 961. The occlusions or non-homogeneities 130 are, for example, small capsules, flakes, grains, or additive grains, or predetermined planned holes, in particular inserted with equidistant spacing.

The continuous filter rod 24 is irradiated on the transmitting side with the aid of a light-transmission method, using the laser light source 122. With the aid of the laser light source 122, a line-shaped ray is directed point-shaped or fan-shaped onto the continuous filter rod 24, so that the light ray enters point-shaped and perpendicular into the continuous filter rod 24. From this point of entry, the light propagates cone-shaped inside the continuous filter rod 24 as a result of scattering, as shown in FIG. 2. The light entering the filter rod 24 at a point or apex of the cone is thus spread out due to the scattering so that a propagation cone is formed that increases in diameter to the side of filter rod 24 where the light exits the continuous filter rod in the region between points A-B.

With the exemplary detection device 100, shown in FIG. 2, the dimension of the planes and/or the spacing between the planes S1, S2 is determined by the propagation cone for light fed into the continuous filter rod 24 and/or the material of the continuous filter rod, the propagation cone for the light source 122, as well as the opening angle shown by lines 111, 112 for the receiving optic on the opposite side of the continuous filter rod 24 from the laser light source 122. Planes S1 and S2 include the point of intersection of the propagation cone for the light fed into the continuous filter rod 24 and the lines 111, 112 indicating the opening angle of the receiving optic. The propagation cone for the light in the continuous filter rod 24 and/or the material is determined by the material properties of the continuous filter rod 24 and/or material and therefore cannot be influenced from outside the filter rod.

A diaphragm 116 is provided on the receiver side of the continuous filter rod 24 in front of the sensor 114, which may be a photodiode in a preferred embodiment. Owing to geometric conditions, light travels at a specific angle from the side where the light exits the continuous filter rod 24, through the diaphragm 116, and onto a photo-sensitive layer in the sensor 114. Transferred to the surface of the filter rod 24, this means that light reaching zone I-II, shown in FIG. 2, travels to the photo-sensitive layer of the sensor 114. That is, only a portion of the light exiting filter rod 24 is evaluated by the receiving optic.

The influence of the opening angle indicated by lines 111, 112 for the receiving optic on the exit side is furthermore minimized by providing an imaging device 126 so that light can pass only through a short section or zone I-II of the continuous filter rod 24 surface and onto the photo-sensitive layer of sensor 114. The imaging device 126 may be in the form of a lens 126, which focuses light onto diaphragm 116. As a result, the spacing between the two planes S1, S2 is reduced.

Once a continuous filter rod 24, provided with at least one non-homogeneous area 130, enters the measuring zone of detection device 100, the beam of light that is transmitted through the continuous filter rod 24 creates a light-dark brightness profile. A light-dark transition is intensified by the non-homogeneous area once it reaches the plane S2. The intensity transition is completed once it passes through the parallel plane S1.

The light emitted by the laser light sources, for example in the red visible range (wavelength approximately 655 nm), passes through the continuous filter rod 24 and impinges on the sensor 114. The electrical signal from the sensor is then fed to an evaluation unit 120. The changes in the brightness profile and/or the signal to be evaluated are detected by means of the evaluation unit 120, thus making it possible to determine by means of the evaluation unit 120 whether the beam path contains a non-homogeneity 130. The brightness profile depends on the differences in the light conductivity of the material in the continuous filter rod 24 and/or the non-homogeneities 130.

The non-homogeneities 130 cause a reduction in the light conductivity, so that the non-homogeneity 130 can be localized and/or detected on the basis of the change in the brightness profile. Using the transporting speed for the continuous filter rod 24, as well as the measured brightness profiles, it is also possible to determine the spacing between the isolated non-homogeneities and, if necessary, also the dimensions of the non-homogeneities 130.

For a secure detection of the non-homogeneities 130 and/or the capsules, the brightness profiles are compared to a predetermined control value or a predetermined control brightness profile. The existence or lack of a non-homogeneity 130 in the continuous filter rod 24 is then determined based on the deviations from these control values.

If, for example following the detection of one non-homogeneity 130, no further non-homogeneity is detected in the continuous filter rod 24 at a predetermined distance to the location of the previously detected non-homogeneity 130, the corresponding section of the continuous filter rod 24 is removed from the further production process during a following production step.

The propagation cone for the light from the laser light source 122, used to irradiate the section A-B on the surface of the continuous filter rod 24, depends on the size of the cone angle. The opening angle indicated by lines 111, 112 for the receiving optic is fixed by the dimensions for the diaphragm 116 and the photo-sensitive layer of the sensor 114.

FIG. 3 shows a different exemplary embodiment of an arrangement for detecting and/or localizing non-homogeneities in a continuous filter rod 24. This embodiment utilizes two detection devices 100, arranged transverse to the conveying direction for the continuous filter rod 24, so that the continuous filter rod 24 is irradiated in a single plane by two laser light sources 122.

As a result of a measuring and/or detecting operation along two axes, these operations can be carried out independent of the axial position of the non-homogeneities 130 in the continuous filter rod 24. In the process, the brightness profiles detected by the sensors 114 are transmitted further to the joint evaluation unit 120. Since the laser light sources 122 and the sensors 114 are arranged in a plane that is positioned perpendicular to the conveying direction for the continuous filter rod, it is possible to determine the precise position of the non-homogeneities in the continuous filter rod 24 on the basis of irradiating the continuous filter rod 24 along two axes.

The invention has been described in detail with respect to preferred embodiments, and it will now be apparent from the foregoing to those skilled in the art, that changes and modifications may be made without departing from the invention in its broader aspects, and the invention, therefore, as defined in the appended claims, is intended to cover all such changes and modifications that fall within the true spirit of the invention. 

1. A device for detecting isolated occlusions in a conveyed continuous rod in the tobacco industry, said device comprising: a light source for irradiating the continuous rod via a light-transmission method with a beam of light; a sensor for receiving the beam of light transmitted through the continuous rod and at least partially detecting areas of brightness caused by irradiation from the light sources in the continuous rod; and an evaluation device for detecting the presence of the isolated occlusions in the continuous rod by evaluating the detected areas of brightness.
 2. The device as defined in claim 1, further comprising an imaging device disposed between the continuous rod and the sensor where the imaging device focuses the areas of brightness caused in the continuous rod on the sensor.
 3. The device as defined in claim 2, wherein the imaging device is provided with at least one optical lens.
 4. The device as defined in claim 2, wherein the light source disposed on one side of the continuous rod, the imaging device disposed on the opposite side of the continuous rod, and the sensor that receives light from the imaging device constitute a measuring device.
 5. The device as defined in claim 4, wherein at least two measuring devices are used to measure the continuous rod.
 6. The device as defined in claim 5, wherein the at least two measuring devices are arranged transverse to the longitudinal axis of the continuous rod.
 7. The device as defined in claim 1, wherein the light source comprise a laser light source.
 8. The device as defined in claim 2, further comprising at least one diaphragm disposed in a path of the light beam between the imaging device and the sensor.
 9. The device as defined in claim 1, wherein the conveyed continuous rod is a continuous filter rod.
 10. The device as defined in claim 6, wherein the at least two measuring devices are arranged in a single plane.
 11. A continuous rod-producing machine used in the tobacco industry, including the device as defined in claim
 1. 12. A method for detecting isolated occlusions in a conveyed continuous rod in the tobacco industry comprising the steps of: irradiating the continuous rod with a light source using a light-transmission method; at least partially detecting brightness caused by the light source in the irradiated rod with a sensor; and determining the presence of isolated occlusions in the continuous rod on the basis of the detected brightness.
 13. The method as defined in claim 12, including imaging, at least in part, the brightness on the sensor by an imaging device.
 14. The method as defined in claim 12, wherein the irradiating step includes irradiating the continuous rod by a laser light source.
 15. The method as defined in claim 12, wherein the irradiating step includes irradiating the continuous rod by at least two laser light sources.
 16. The method as defined in claim 12, wherein the irradiating step includes irradiating the number of occlusions the locations of the occlusion via the detected brightness.
 17. The method as defined in claim 12, including removing at least a section of the continuous rod if values for the detected brightness deviate from predetermined control values.
 18. The method as defined in claim 12, wherein the determining step includes detecting the presence of occlusions in the continuous rod via an evaluation unit.
 19. A method of producing a continuous rod in a machine used in the tobacco industry, comprising utilizing the device according to claim 1 to detect isolated occlusions in the continuous rod as it is conveyed in the machine. 